Chidamide inhibits t(8;21) AML cell proliferation and AMK1/ETO and C-KIT expression by inhibiting ERK1/2 signaling pathway

Background: t(8;21) acute myeloid leukemia (AML) is a highly heterogenous hematological malignancy. Histone deacetylases inhibitors (HDACi) are a group of small-molecule compounds with extensive anti-tumor activity. Chidamide (CS055) is a selective HDACi independently developed by China. We aimed to investigate its anti-tumor activity and mechanism in t(8;21) AML cells.

Methods: Human AML SKNO-1 cells were transfected with AML1/ETO-siRNA to obtain SKNO-1-si-A/E cells. Human acute monocytic leukemia U937 cells were transfected with AML1/ETO fusion gene to obtain U937-A/E cells. AML1/ETO-positive (Kasumi-1, U937-A/E and SKNO-1) and AML1/ETO-negative AML cells (HL-60, U937, SKNO-1-siA/E) were treated with chidamide (0.125, 0.25 and 0.5 µM). Cell proliferation was evaluated by CCK-8 assay. Cell apoptosis and cell cycle was detected by flow cytometry. Microarray profiling of SKNO-1 cells was performed. The level of histone 3 acetylation and ERK1/2 phosphorylation was determined by Western blot. AML1/ETO and C-KIT mRNA expression was detected by real time quantitative PCR (RT-qPCR). Kasumi-1 and SKNO-1 cells were treated with U0126, a special inhibitor of ERK1/2, and cell proliferation and ERK1/2 phosphorylation level was examined.

Results: Chidamide inhibited the proliferation, induced cell cycle arrest, and stimulated cell apoptosis of AML1/ETO-positive AML cells. Microarray profiling showed that 13 differentially expressed genes were involved both in the "ERK1/2" pathway and "apoptosis" functions. Chidamide inhibited histone 3 acetylation and ERK1/2 phosphorylation in AML1/ETO-positive AML cells. U0126 inhibited the proliferation of AML1/ETO-positive AML cells via regulating the ERK1/2 pathway.

Conclusions: Our results suggested that chidamide inhibits t(8;21) AML cell proliferation and AMK1/ETO and C-KIT expression by inhibiting ERK1/2 signaling pathway.